The present invention relates to write strategy tuning of an optical storage device, and more particularly, to methods and systems for tuning write strategy parameters utilizing data-to-clock edge deviations.
As multimedia applications continue to progress, the demand for storing massive digital data increases rapidly. As a result, high storage volume and compact size optical storage media such as Compact Discs (CDs) or Digital Versatile Discs (DVDs) are very popular, and optical storage devices such as CD drives or DVD drives have become standard accessories of personal computers, utilized for performing the multimedia applications.
Take the CD drive as an example. When the CD drive is controlled to write data to a CD-Recordable (CD-R) disc, the writing power of a laser diode in the CD drive is usually set to be a specific value, and write pulses corresponding to the data are utilized for recording pits and lands onto the grooves of the CD-R disc. The specific value of the writing power can be derived from an optimal power calibration (OPC) process. On the other hand, through a write strategy tuning process, which is also referred to as a recording strategy tuning process, changing write strategy parameters for controlling widths of the write pulses may increase the accuracy of lengths of pits and lands formed on the CD-R disc. Please refer to related documents of the CD-R specifications (e.g. the Orange Book Part I) for more information.
According to the related art, a specific device such as an oscilloscope can be utilized during the write strategy tuning process. Usually, according to an eye pattern of a plurality of reproduced waveforms shown on the oscilloscope after a trial writing process in advance, a new set of write strategy parameters for controlling the widths of the write pulses are determined, based on experience, by an engineer or researcher. It takes a lot of engineer or researcher's time to utilize this method because the same process must be repeatedly performed for various applicable media and different recording speeds, including at least writing test data, inspecting an eye pattern of reproduced waveforms shown on the oscilloscope, and determining a new set of write strategy parameters by experience according to the eye pattern. The write strategy tuning process mentioned above is time consuming since determining the write strategy parameters by inspecting eye patterns is not an automatic operation. In addition, the write strategy tuning process mentioned above is indefinite since determining a new set of write strategy parameters by experience according to the eye pattern is not quantitative. Under certain situations, an unclear eye pattern would invalidate or interfere with the write strategy tuning process.
A specific instrument such as a time interval analyzer (TIA) or a jitter meter might be helpful for the purpose of deriving information for determining a new set of write strategy parameters. However, similar routine work is also required, and if the TIA or jitter meter is simply coupled for measuring without setting up an additional control system, the same drawbacks caused by the manual tuning process still existed. In addition, the information derived from the specific instrument is usually implicit and therefore takes up a large amount of experienced engineer or researcher's time.